Electric railway speed control

ABSTRACT

Regenerative braking systems which have previously been used in association with electrically driven vehicles have been manually controlled whereas the present invention provides a governor which automatically controls the starting resistance of the series winding of the motor and the regenerative braking resistance of the motor in proportion to the speed of the vehicle. The starting resistance means and the braking resistance means vary in a series of steps which progressively decrease the starting and braking resistance as the speed of the vehicle increases and progressively decreases the starting and braking resistance as the speed of the vehicle decreases within predetermined limits so that the variation in the starting resistance is effective in the low speed range while the variations in the braking resistance are effective in the high speed range. In addition, the governor of the present invention is mounted directly onto the output drive shaft of the motor so that there is no danger of failure of the governor as a result of a failure of any transmission used to transmit power to the governor which might otherwise permit the motor to rotate at high speed while the governor is inoperative.

United States Patent [19] Bradley 1 1 Feb. 26, 1974 1 ELECTRIC RAILWAY SPEED CONTROL .[761 lnventor: Robert Auldom Bradley, 18 Ralston Ave., Toronto 13, Ontario, Canada 221 Filed: Nov. 24, 1972 211 App]. No.: 309,061

[30] Foreign Application Priority Data Feb. 10,1972 Canada 134456 [52 U.S.Cl..... ..3l8/270,318/376 [51 Int. Cl. ..l-l02p 1/20,H02p 3/14 [58] Field of Search 290/3, 9, 45; 318/87, 139, 318/269, 270, 272, 273, 275,376, 396, 397,

Hoffman 318/87 X Primary Examiner--Bernard A. Gillieany Assistant ExaminerW. E. Duncanson, Jr. Attorney, Agent, or FirmFetherstonhaugh & Co.

' [57 ABSTRACT Regenerative braking systems which have previously been used in association with electrically driven vehicles have been manually controlled whereas the present invention provides a governor which automatically controls the starting resistance of the series winding of the motor and the regenerative braking resistance of the motor in proportion to the speed of the vehicle. The starting resistance means and the braking resistance means vary in a series of steps which progressively decrease the starting and braking resistance as the speed of the vehicle increases and progressively decreases the starting and braking resistance as the speed of the vehicle decreases within predetermined limits so that the variation in the starting resistance is effective in the low speed range while the variations in the braking resistance are effectivein the high speed range. In addition, the governor of the present invention is mounted directly'onto the output drive shaft of the motor so that there is no danger of failure of the governor as a result of a failure of any transmission used to transmit power to the governor which might otherwise permit the motor to rotate at high speed while the governor is inoperative.

6 Claims, 3 Drawing Figures PAlENIEnfmzslm 794,897

sum 2 0r 2 FIG. 3

ELECTRIC RAILWAY SPEED CONTROL This invention relates to self-propelled electric railway cars. In particular, this invention relates to im-- provements in self-propelled electric railway cars in corporating a regenerative braking motor and a governor for controlling the operation of the motor.

In my prior Canadian Pat. No. 647,365, dated Aug. 28, 1962, I described an electric railway apparatus wherein the individual cars are driven 'by an electric motor which is directly connected to the wheel axle. I

have also described the method of supplying power to the motor and the method of insulating the motor relative to the power supply. In my prior patent I have described electric railway apparatus which is suitable for use without the assistance of an operator. One of the problems associated with the operation of vehicles without the assistance of an operator is to ensure that the vehicle will start, brake and stop in a manner which willpermit the safe operation of the vehicle. It is important to ensure that when an unmanned electric vehicle slows down as a result of an increased load applied when the vehicle encounters an upward incline, the power supplied to the motor is adjusted accordingly and also it is important to adjust the power supplied to a motor when travelling at high speed in order toprevent damage to the motor resulting from over-driving the motor.

It is well known to use various resistances in a starter for an electric motor and regenerative braking systems have also been provided for electric locomotives and the like to effect braking and to prevent over-running of the motor. However, the known regenerative braking systems are controlled by the operator of the vehicle and no system has yet been provided which will operate automatically without an operator. A further problem with the known starter series resistance systerns and regenerative braking systems has been in attempting to privide for the operation of these systems in direct response to the rotation of the motor drive shaft so that failure of a gear transmission systemdisposed intermediate the drive motor and the control mechanismsfor controlling the operation of the starter system and the regenerative braking system cannot'occur.

' The present invention overcomes the difficulties of the prior art described above and provides a governor which automatically controls the speed of the car by automatically regulating the starting resistance and vregenerative braking resistance in a predetermined manner with respect to the speed of the car.

In addition, the present invention provides a governor for use in association with a self-propelled electric railway car or the like wherein the power supplied to the drive motor and the regenerative braking of the motor is provided in a series of steps which are balanced against an appropriate speed of the motor.

Furthermore, the governor of the present invention may be mounted directly on the drive shaft of the motor so that the dangers associated with the usual transmission of power to the governor are eliminated.

The present invention also provides a braking system which is operable by means of the governor at excessive speeds of the motor to apply a conventional brake to the vehicle.

According to an embodiment of the present invention, there is provided, in a self-propelled electric railway car or the like which has a series winding and a regenerative field winding which are not directly connected to one another, starting resistance means for the series winding and regenerative braking resistance means for the regenerative field winding of the motor, the improvement of governor means operative in response to a predetermined speed of said car to control the starting resistance means and the braking resistance means as required in use.

The invention will be more clearly understood after reference to the following detailed specification read in conjunction with the drawings, wherein FIG. 1 is a partially sectioned view of a governor and starting resistance means and braking resistance means according to an embodiment of the present invention;

FIG. 2 is a sectional view taken along the line 2-2 of FlG. 1i and a A FIG. 3 is a partially sectioned view illustrating the manner in which the apparatus of the present invention is mounted on a vehicle. I

As shown in FIG. 3 of the drawings, a vehicle having a frame generally identified by the reference numeral 10 has a pair of wheels 12 which support the vehicle on rails 14 and 14a. The wheels 12 are mounted on a common axis. A regenerative motor 16 is mounted on the frame 10 by suitable means (not shown) so that the housing of the motor is stationary relative to the frame.

The motor 16 has output drive shafts 18 extending from opposite ends thereof and a pair of solenoid operated brakes 20 are mounted on the shafts 18. The brakes 20 may be of the well known type operated by a solenoid in order to effect braking of the motor drive shaft 18. The rail 14a is connected to a dc power supply and in order to insulate the motor 16 from the power supply, an insulated coupling22 is provided in the shaft 18. A contactor wheel 24 is provided on the shaft 18 outwardly from the coupling 22 and contactor 26 is mounted on the shaft 18 on the opposite side of the motor and adjacent to the governor 28. A rheostat 30, which will be described hereinafter, is connected in the series circuit of the motor 16 and rheostat 32 is connected in the field winding circuit of the motor 16. Support arms 34 and 36 are mounted on the motor 16 and project outwardly therefrom towards the rail 14 so as to overlie the governor 28.

The governor 28 and associated rheostats 30 and 32 form a principal feature of the present invention and are more clearly illustrated in FIGS. land 2.

With reference to FIG. 1 of the drawings, it will be I seen that the governor which is generally identified by the reference numeral 28 consists of a base plate 40 which is secured to the shaft 18 for rotation therewith, a collar plate 42 a pair of governor balls 44 mounted on arms 46, a sleeve 48, springs 50 and 52, and a pair of laterally projecting arms 54 and 56 extending outwardly from the slip ring 62. The sleeve 48 is rigidly keyed to the shaft 18 by means of a key 58 so that the sleeve 48, governor balls 44, arms 46, collar plate 42 and base plate 40 will rotate with the shaft 18 in use. The arms 54 and 56 are connected by means of a slip ring 62 which is a sliding fit in the annular recess 60 formed in the sleeve 48. An important feature of the rotating governor assembly is the provision of springs 50 and 52 of different compressive strengths so that the initial movement of the governor will be primarily conpassage 120 towards the second contact 122, When trolled by the lightweight compression spring 50 while a bracket 70 whichextends laterally from the support 64 so as to extend outwardlytowards the shaft 18.The spring-like arms 68 increase in length in a direction towards the governor balls. Adjustment screws 72 are provided at the inner end of the arm 66 so as to adjust the spacings between the arms 68 to control the timing of the operation of the device as will be described hereinafter. An anvil-like member 74 is mounted on the bracket 34 and projects upwardly therefrom behind the arms 68. The support block 70 and the inner ends of the adjustment screws 72 are made from an insulating material so that each of the spring-like arms 68 is insulated from one another when in the spaced position shown in FIG. 1 of the drawings. The arm 56 which projects outwardly from the slip ring 62 has a contact member 80 at the outer end thereof which is insulated with respect to the remainder of the arm and which is connected to a power source by means of the line 82. The first, second, third and fourth arms 68 are cnnected to solenoids 92, 94, 96 and 98, respectively, and the last arm 68 is connected to solenoid 100, as shown in FIG. 1. The field winding 102 of the motor is con nected to a power source by way of line 104 and resistances R1, R2, R3 and R4, depending upon the operation of the solenoids 92, 94, 96 and 98. The emergency brake is connected to a power source by way of line 106 and the power supplied to the brake is interrupted by the solenoid 100 when braking is not required.

The arm 36 on the other side of the shaft 18 is formed with a plurality of recessed channels 120 within which sliding contact members 122 are reciprocally mounted.

The sliding contact members 122 are connected to the thereof so as to be alignable with each of the contacts 122. The power supply to'the series winding of the motor is controlled by the rhcostat, diagrammatically illustrated at 30in FIG. 1, which includes solenoids,

130, 132, 134, 136 and 138, each of which is connected to a contact 122. The power supply to the series winding of the motor is supplied directly through line 140 or through resistances R5, R6, R7, R8 and R9, .de-

pending upon the'position of the solenoid switches 130',

To start the forward motion of the vehicle, power is supplied to the series winding by way of the rail 14a, wheel 12, contact wheel 24, line 140 and resistances R5, R6, R7, R8 and R9. As the vehicle begins to move, the governor balls are rotated and as the vehicle gathers speed, the governor balls move outwardly causing the collar 48 to move towards the sleeve member 42. The contact 126 will eventually make contact with the first contact 122, thereby activating the-solenoid 130 to remove resistance R5, thereby increasing the power supplied to the motor. As the vehicle picks up more speed, the first contact 122 is moved within the slide contact is made with the second contact 122, the second solenoid 132 will be activated removing the resistance R6, with the result that boththe resistances R5 and R6 will be removed from the circuit thereby furtheir increasing the power supplied to the motor. A further increase in speedwill remove the resistances R7,

. R8, R9 from the circuitrThe movement of the'governor,

over theperiod during which contact is made with the various contacts 122 is primarily controlled by the lightweight spring 50. However, after all of the contacts 122 have been brought into use, the spring 50 is substantially fully compressed and'the further movement of the collar is controlled by the heavier compressive spring 52. The use of this double spring assembly permits the starting resistance means to operate in response to a substantial movement of the contact arm 54 for a relatively low increase in speed of the vehicle. All of the'starting resistances will be removed from the series circuit by the time the vehicle has reached a relatively low starting speed in the range of about 5 to 18 miles per hour for a self-propelled electric railway car orthelike. i a

With full power being supplied to the motor'and the car running on a level'track, the car will gather speed until at a predetermined maximum speed the governor I continue to operate to cause the arm 56 to move so as to cause the contact 80 to make contact with both the first and second arm 68,'there'by activating the solenoid 94 to remove resistance R1 from the regenerative braking circuit. Further acceleration of the vehicle will activate solenoids 96 and 98, removing resistances R2 and R3 from the regenerative braking circuit, thereby in.- creasing the braking effect of the regenerative braking circuit on the motor.' If the vehicle continues to accelcrate, the contact 80 will eventually be placed in contact with all of the 'arms 68 so that eventually the solenoid will be activated which will connect the emergency brakes 20 to the power source by means of the line 106, thereby applying a direct braking force to the axle of the vehicle. 7 1

As the vehicle begins to slow dovvinthe operation of I the governor willbe the reverse tothat previously described above sothat if initially the governor is in a position to apply'the emergency braking system as described above, slowing will initially release the emergency brake system and subsequently remove the regenerative braking load from the motor until the required cruising speed is obtained. Generally the motor will have sufficient power to drive the vehicle up any predetermined incline in its path. As the vehicle slows down below the cruising speed, the operation of the starting circuit will be reversed from that previously described in that the resistances R9, R8, R7, R6 and R5 will be added to the power supply line as a result of disengagement of the contact 126 with successive contacts 122.

may be particularly suitable for use in railwayvvehicles for use in northern areas wherein railway cars may be transported over long distances without requiring an operator. There are considerable advantages resulting from the use of a railway system as opposed to, for ex-' ample, a pipe line in northern areas due to the fact that a failure in a pipe line conveying oil or the like may result in spillage of enormous quantities of oil before the leakage is detected whereas in the event of a failure in a track vehicle, the only damage likely to occur will be as a result of a derailment of a number of tank cars and techniques for controlling and preventing derailments of railway cars are well known and highly developed.

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

1. In a self-propelled electric. railway car or the like having drive wheel means for driving the car along a track and'mechanical brake means for braking the car, the improvement of: regenerative braking motor means having output shaft means drivingly connected to said drive wheel means of said car, said regenerative motor means having a series winding and a regenerative field winding which are not directly connected to one another, starting resistance means for said series winding of said motor, regenerative braking resistance means for said regenerative field winding of said motor, mechanical governor means mounted on said drive shaft of said motor and operative in response to rotation of said drive shaft to control said starting resistance means and said braking resistance means as required in use.

2. In a self-propelled-electric railway car which has a regenerative braking motor means having a series winding and a regenerative field winding which are not directly connected to one another, starting resistance means for said series winding of said motor, regenerative braking resistance means for said regenerative field winding of said motor, the improvement of mechanical governor means operative in response to a predetermined speed of said car to control said starting resistance and said braking resistance as required in use,

6 said mechanical governor being a two-stage governor, the first stage being operative at slow speeds to effect a step variation in said starting resistance which is balanced against the appropriate speed of said car, the second stage being operative at high speed to effect a step variation in the regenerative braking resistance which is balanced against the appropriate speed of the car. I,

3. A self-propelled railway car as claimed in claim 7 having mechanical braking means, said governor means being operative to activate said mechanical braking means for said car at a predetermined speed of said car.

4. In a self-propelled electric railway car or the like .having drive wheel means for driving the car along a track andmechanical brake means for braking the car, the improvement of; regenerative braking motor means having output shaft means drivingly connected to said drive wheel means of said car, said regenerative motor means having a series winding and a regenerative field winding which are not directly connected to one another, starting resistance means for said series winding of said motor, regenerative'braking resistance means for said regenerative field winding of said motor, mechanical governor means mounted on said drive shaft of said motor and operative in response to rotation of said drive shaft to control said starting resistance means and said braking resistance means as required in use, said governor being a two-stage governor, the first stage being operative at slow speeds to effect a step variation in said starting resistance which is balanced against the appropriate speed of said motor, the second stage being operative at high speed to effect a step variation in the regenerative braking resistance which is balanced against the appropriate speed of the motor.

5. A self-propelled railway car as claimed in claim 4 wherein said governor means is operative to activate said mechanical braking means for said car at a predetermined speed'of rotation of said shaft.

6. A self-propelled electric railway car having a propulsion unit comprising regenerative braking motor means having a series winding and a regenerative field winding which are not directly connected to one another, starting resistance means for said series winding of said motor, regenerative braking resistance means for said regenerative field winding of .said motor, mechanical governor means operative in response to a predetermined speed of said car to control said starting resistance and said braking resistance as required in use. 

1. In a self-propelled electric railway car or the like having drive wheel means for driving the car along a track and mechanical brake means for braking the car, the improvement of: regenerative braking motor means having output shaft means drivingly connected to said drive wheel means of said car, said regenerative motor means having a series winding and a regenerative field winding which are not directly connected to one another, starting resistance means for said series winding of said motor, regenerative braking resistance means for said regenerative field winding of said motor, mechanical governor means mounted on said drive shaft of said motor and operative in response to rotation of said drive shaft to control said starting resistance means and said braking resistance means as required in use.
 2. In a self-propelled electric railway car which has a regenerative braking motor means having a series winding and a regenerative field winding which are not directly connected to one another, starting resistance means for said series winding of said motor, regenerative braking resistance means for said regenerative field winding of said motor, the improvement of mechanical governor means operative in response to a predetermined speed of said car to control said starting resistance and said braking resistance as required in use, said mechanical governor being a two-stage governor, the first stage being operative at slow speeds to effect a step variation in said starting resistance which is balanced against the appropriate speed of said car, the second stage being operative at high speed to effect a step variation in the regenerative braking resistance which is balanced against the appropriate speed of the car.
 3. A self-propelled railway car as claimed in claim 7 having mechanical braking means, said governor means being operative to activate said mechanical braking means for said car at a predetermined speed of said car.
 4. In a self-propelled electric railway car or the like having drive wheel means for driving the car along a track and mechanical brake means for braking the car, the improvement of; regenerative braking motor means having output shaft means drivingly connected to said drive wheel means of said car, said regenerative motor means having a series winding and a regenerative field winding which are not directly connected to one another, starting resistance means for said series winding of said motor, regenerative braking resistance means for said regenerative field winding of said motor, mechanical governor means mounted on said drive shaft of said motor and operative in response to rotation of said drive shaft to control said starting resistance means and said braking resistance means as required in use, said governor being a two-stage governor, the first stage being operative at slow speeds to effect a step variation in said starting resistance which is balanced against the appropriate speed of said motor, the second stage being operative at high speed to effect a step variation in the regenerative braking resistance which is balaNced against the appropriate speed of the motor.
 5. A self-propelled railway car as claimed in claim 4 wherein said governor means is operative to activate said mechanical braking means for said car at a predetermined speed of rotation of said shaft.
 6. A self-propelled electric railway car having a propulsion unit comprising regenerative braking motor means having a series winding and a regenerative field winding which are not directly connected to one another, starting resistance means for said series winding of said motor, regenerative braking resistance means for said regenerative field winding of said motor, mechanical governor means operative in response to a predetermined speed of said car to control said starting resistance and said braking resistance as required in use. 